JP4819782B2 - Internal combustion engine speed control device for work machine - Google Patents

Description

  The present invention relates to an internal combustion engine speed control device for a work machine, and in particular, a work machine that contributes to an improvement in smoke concentration during free accelerator operation in a work machine such as a construction machine equipped with an all-speed control type internal combustion engine. The present invention relates to an internal combustion engine speed control device.

  Construction machines such as hydraulic excavators and work machines such as large dump trucks generally include a diesel engine (hereinafter referred to as an engine as appropriate) as an internal combustion engine, and at least one variable displacement hydraulic pump is driven to rotate by this engine. The hydraulic actuator is driven by the pressure oil discharged from the hydraulic pump to perform necessary work. For example, as described in Patent Document 1 (Japanese Patent Publication No. 62-8620), this engine includes a target rotational speed signal from a target rotational speed setting means such as an engine control dial and an actual rotational speed signal from a rotation sensor. The fuel injection amount is controlled based on the rotational speed deviation signal, and the engine rotational speed and the engine output torque are controlled. A system that controls the fuel injection amount of the internal combustion engine based on the rotational speed deviation signal between the target rotational speed signal and the actual rotational speed signal is referred to as an all speed control system. In recent years, an electronic governor that electronically controls the fuel injection amount is often used as the fuel injection amount control means.

  Diesel engines also have a problem of deterioration in smoke concentration, such as an increase in the amount of black smoke generated during so-called free accelerator operation in which the target engine speed is rapidly increased while the internal combustion engine is almost unloaded. Conventionally, various proposals have been made for improving such a flue gas concentration. Examples thereof include Patent Document 2 (Japanese Patent Laid-Open No. 2-206302), Patent Document 3 (Japanese Patent Laid-Open No. 2000-345885), and There exists what was disclosed by patent document 4 (Unexamined-Japanese-Patent No. 2001-355489).

<Patent Document 2 (Japanese Patent Laid-Open No. 2-206302)>
The device described in Patent Document 2 stores a torque command pattern that suppresses the exhaust particle concentration based on the rotational speed of the internal combustion engine and the exhaust particle concentration characteristic unique to the internal combustion engine, and the rotation of the internal combustion engine is stored in the torque command pattern. While obtaining the corresponding torque command value by referring to the speed, the drive torque reduction signal having a magnification corresponding to the depression angle of the accelerator pedal is obtained, and the torque command value is multiplied by the drive torque reduction signal to obtain the low rotation region of the internal combustion engine. Drive torque command value calculating means for obtaining a drive torque command value that results in a low exhaust particle concentration over the entire rotation region, and driving an electric motor connected to the main shaft of the internal combustion engine so as to obtain the drive torque command value By assisting the drive torque, the internal combustion engine generates a large torque according to its autonomous injection amount control, especially in the low speed region It was suppressed, in which to fit the desired smoke density.

<Patent Document 3 (Japanese Patent Laid-Open No. 2000-345885)>
The apparatus described in Patent Document 3 includes means for determining a basic fuel injection amount based on the engine speed and accelerator opening, means for determining a maximum fuel injection amount based on the engine speed and intake air amount, In the fuel injection device for a diesel engine having means for comparing the fuel injection amount and the maximum fuel injection amount and setting the smaller one as the target fuel injection amount, there are two conditions that the vehicle speed is zero and the accelerator opening is not zero. A determination means for determining whether or not the condition is satisfied, and when the two conditions are satisfied, the maximum fuel injection amount is corrected to be reduced to a new maximum fuel injection amount, which is a target for comparison with the basic fuel injection amount. And reducing the fuel injection amount with a new maximum fuel injection amount that has been corrected for the reduction when the engine is blown. Thereby preventing the click occurred.

<Patent Document 4 (Japanese Patent Laid-Open No. 2001-355489)>
The apparatus described in Patent Document 4 stores a running state detection unit that detects a running state of a vehicle, and an injection amount control characteristic during traveling of the vehicle that determines a fuel injection amount during traveling of the vehicle according to the operating state of the internal combustion engine. First control characteristic storage means for determining the fuel injection amount when the vehicle is stopped according to the operating state of the internal combustion engine; second control characteristic storage means for storing an injection amount control characteristic when the vehicle is stopped; An injection amount control characteristic switching means for switching from an injection amount control characteristic when the vehicle is running to an injection amount control characteristic when the vehicle is stopped when it is detected that the vehicle has stopped. By specifying the fuel injection amount to be smaller than the fuel injection amount when the vehicle is running, racing (blank) is performed when the internal combustion engine is in a no-load state without causing a decrease in output when the vehicle is running. Exhaust of black smoke when going It is intended to reduce the amount.

Japanese Examined Patent Publication No. 62-8620 JP-A-2-206302 JP 2000-345885 A Japanese Patent Laid-Open No. 2001-355489

  As described above, the device described in Patent Document 2 (Japanese Patent Laid-Open No. 2-206302) has a predetermined exhaust particle concentration based on the rotational speed of the internal combustion engine and the exhaust particle concentration characteristic unique to the internal combustion engine. While obtaining the torque command value corresponding to the rotational speed at that time from the torque command pattern to be suppressed, a drive torque reduction signal with a magnification from zero to 1 corresponding to the depression angle of the accelerator pedal is obtained, and multiplied by them to calculate the motor A drive torque command value is obtained, and the motor is driven to assist the drive torque so that the drive torque command value is obtained. During the assist drive by the electric motor, no special control for reducing the smoke concentration is performed on the internal combustion engine.

Incidentally, the control of the fuel injection amount of an internal combustion engine (diesel engine) mounted on a normal vehicle as described in Patent Document 2 is a so-called minimum maximum speed in which the fuel injection amount is determined based on the accelerator opening and the rotational speed. The characteristics of the control method are adopted. In the minimum maximum speed control method, the output torque characteristic is set so that the maximum output torque changes according to the depression angle of the accelerator pedal, so when operating to the opening of the intermediate region where the depression angle of the accelerator pedal is not the maximum, The fuel injection amount changes according to the output torque characteristics corresponding to it, and moves from the equilibrium point with the drag resistance of the load connected to the internal combustion engine to a new equilibrium point. As a result of stopping at the fuel injection amount corresponding to the angle, there is no excessive injection amount. As a result, the apparatus of Patent Document 2 is special for the internal combustion engine only by driving the motor and assisting the drive torque at the time of so-called free acceleration in which the internal combustion engine increases the target rotational speed rapidly with almost no load. Even if the control is not performed, it is possible to prevent the internal combustion engine from generating a large torque especially in the low speed region in accordance with the autonomous injection amount control, and to prevent the smoke concentration from deteriorating.

On the other hand, in the so-called all-speed control type internal combustion engine as described in Patent Document 1 (Japanese Patent Publication No. 62-8620) normally used for construction machines, the target rotational speed and the actual rotational speed are set over the entire rotational speed range. since the fuel injection amount is determined in accordance with the rotational speed deviation is the difference, even in the case of operating the accelerator as described above the intermediate region, by operating the control dial at normal speed, the rotation speed deviation signal suddenly increases As a result, the fuel injection amount reaches a new equilibrium point after the maximum state has elapsed. Accordingly, since the engine is operated with the maximum injection amount from the low speed range, the smoke concentration is deteriorated and the noise and fuel consumption are also adversely affected.

  In the devices described in Patent Document 3 (Japanese Patent Laid-Open No. 2000-345885) and Patent Document 4 (Japanese Patent Laid-Open No. 2001-355589), the fuel control method of the internal combustion engine determines the fuel injection amount based on the accelerator opening and the rotational speed. On the premise of the so-called minimum maximum speed control system to be determined, the maximum fuel injection amount is corrected to decrease to a new maximum fuel injection amount (Patent Document 3), or the fuel injection amount when the vehicle is stopped It is defined so that the fuel injection amount is smaller than the fuel injection amount (Patent Document 4), and so-called as described in Patent Document 1 (Japanese Patent Publication No. 62-8620) normally used for construction machines and the like. This technology cannot be applied to all speed control internal combustion engines.

  Also, in the technology itself of Patent Document 3, when the correction coefficient for correcting the reduction in the maximum fuel injection amount is small, the smoke concentration can be suppressed to a small value, while the time required to reach the required engine speed is reached. On the other hand, if the correction coefficient is set to a large value close to 1, an increase in the time required to reach the required engine speed can be suppressed, but the smoke concentration is deteriorated. Therefore, it is difficult to satisfy both the smoke concentration and the time required to reach the required engine speed.

  In the technique of Patent Document 4, if the maximum fuel injection amount when the vehicle is stopped can be set to a small value, the concentration of flue gas can be suppressed to a small value. On the other hand, the time required to reach the required engine speed becomes long. Increasing the maximum fuel injection amount when the vehicle is stopped can suppress an increase in the time required to reach the required engine speed, but the smoke concentration will deteriorate. Eventually, it is difficult to satisfy both the flue gas concentration and the time until the required engine speed is reached, as in the technique of Patent Document 3.

  Further, the technique described in Patent Document 2 is combined with the techniques described in Patent Document 3 and Patent Document 4 and applied to a so-called all-speed control type internal combustion engine as described in Patent Document 1 to perform assist drive by an electric motor. In addition, when considering the control of the fuel injection amount of the internal combustion engine between the free accelerator state and the normal use state, the equilibrium point when the assist drive by the electric motor is stopped is the output torque of only the internal combustion engine. Since the deviation from the equilibrium point with the drag resistance (external load) is normal, the fuel injection amount to the internal combustion engine at the moment when the assist drive by the motor is stopped is the fuel injection in the state where the assist drive is performed by the motor. The amount of fuel is rapidly changed from the amount to the fuel injection amount corresponding to the rotational speed deviation signal at that time. For this reason, until reaching a new equilibrium point where the output torque and drag resistance of only the internal combustion engine are balanced, there is an unavoidable adverse effect that the black smoke density deteriorates and the noise increases. In order to avoid this, it is possible to limit the temporal change of the fuel injection amount. However, if the output torque and drag resistance of the internal combustion engine alone are away from a new equilibrium point, a new There is a problem that takes time to reach the equilibrium point.

  A first object of the present invention is a construction machine equipped with a so-called all-speed control type internal combustion engine, in which a motor generator is operated during a so-called free accelerator operation in which the target engine speed is rapidly increased while the internal combustion engine is almost unloaded. An object of the present invention is to provide an internal combustion engine speed control device for a construction machine that can improve smoke density by assist drive and suppress increase in noise and fuel consumption.

  The second object of the present invention is that a construction machine equipped with a so-called all-speed control type internal combustion engine is operated by a motor generator during a so-called free accelerator operation in which the internal combustion engine rapidly increases a target rotational speed with almost no load. The internal combustion engine speed control of the construction machine can improve the flue gas concentration by assist driving, suppress the increase of noise and fuel consumption, and can quickly converge to the equilibrium point with the drag resistance when driving only the internal combustion engine. Is to provide a device.

(1) In order to achieve the first and second objects, the present invention provides an internal combustion engine, a work machine driven by the internal combustion engine, and a work machine operation command means for outputting an operation command for the work machine. When the a target rotational speed setting means for outputting a target speed signal for setting a fuel injection amount control means for adjusting the fuel injection amount of the internal combustion engine, the target rotational speed of the internal combustion engine is operated the target rotation speed setting means for increasing or decreasing the target rotation speed, and an actual rotation speed detecting means for detecting an actual rotational speed of the internal combustion engine, the target rotational speed signal from the target rotational speed setting means and by In the internal combustion engine rotational speed control device for a work machine that commands the fuel injection amount control means to the first fuel injection amount based on a rotational speed deviation signal that is a difference signal from the actual rotational speed signal from the actual rotational speed detection means. The internal combustion engine A connected motor generator, a power storage means connected so as to be able to transmit power between the motor generator, a power conversion means installed between the motor generator and the power storage means, and the rotational speed A mode in which the first fuel injection amount based on the deviation signal is commanded to the fuel injection amount control means is set as the first mode, and separately from this, it roughly matches the drag resistance of the load connected to the internal combustion engine. A second mode in which a second fuel injection amount for generating output torque is commanded to the fuel injection amount control means is set, the work implement operation command means is not operated, and the target rotational speed setting means is a target rotational speed. When operated in the increasing direction, the mode is switched to the second mode, the second fuel injection amount is commanded to the fuel injection amount control means, and a torque command based on the rotation speed deviation signal is output to the power conversion means. do it And control means for the electric power from the serial accumulator to drive the motor generator, the control means, after switching to the second mode, operation of the target speed increasing direction of the target rotational speed setting means When the engine speed is stopped and the rotation speed deviation signal enters a predetermined range, the fuel injection amount commanded to the fuel injection amount control means is gradually increased from the second fuel injection amount, and the power conversion means The torque command is gradually reduced, finally the control mode of the fuel injection amount control means is shifted to the first mode, and the fuel injection amount control means is instructed about the first fuel injection amount in the first mode. and a shall be stopped output of the torque command to the power converter.

Thus, when the work implement operation command means is not operated and the target rotation speed setting means is operated in the target rotation speed increasing direction (at the time of free accelerator operation), not only is the assist drive driven by the motor generator, Since the fuel injection amount control of the internal combustion engine is switched to the second mode in which the second fuel injection amount for generating the output torque roughly corresponding to the drag resistance of the load connected to the internal combustion engine is commanded to the fuel injection amount control means. The fuel injection amount of the internal combustion engine is suppressed to the minimum fuel injection amount commensurate with the drag resistance, and the deterioration of the flue gas concentration and the increase in noise and fuel consumption are suppressed. At this time, the motor generator is driven based on the torque command based on the rotation speed deviation signal, and the internal combustion engine receives the assist drive torque by the motor operation of the motor generator. The speed can be quickly increased to the vicinity of the target rotational speed.

In addition, when shifting to the driving of only the internal combustion engine in the first mode, a process of gradually increasing the fuel injection amount and gradually decreasing the torque command (control convergence process) allows the engine speed to be close to the target engine speed. Since the assist drive by the motor / generator is smoothly stopped after reaching this point and the operation state is restored based on the rotational speed deviation signal of only the normal internal combustion engine, a new balance between the output torque of the internal combustion engine and the drag resistance is achieved. It quickly converges to the equilibrium point and suppresses the deterioration of the flue gas concentration and the increase in noise at that time.

(2) Oite above (1), preferably, the control means, in said second mode, calculating a torque command from the torque characteristics set to the torque command increases in response to increase of the rotational speed deviation signal Based on this torque command, a torque command for the power conversion means is determined.

  As a result, the assist drive torque due to the motor operation of the motor generator is determined corresponding to the rotational speed deviation signal that defines the output torque of the internal combustion engine, so that the torque characteristics of the motor generator and the internal combustion engine can be accurately matched. And accurate control can be realized.

( 3 ) In the above ( 2 ), preferably, the torque characteristic corresponds to the first fuel injection amount in the first mode in a region where a torque command increases in accordance with an increase in the rotation speed deviation signal. It is set to approximate the torque characteristics of the internal combustion engine.

  Thus, by approximating both torque characteristics, the assist drive of the motor generator is stopped, and the operation at the time of shifting to the first mode in which the internal combustion engine is operated based on the first fuel injection amount based on the rotation speed deviation signal. The point (equilibrium point) is close to the equilibrium point between the output torque of the internal combustion engine only and the drag resistance, and the operation can be smoothly shifted to the operation of only the internal combustion engine.

( 4 ) Further, in the above ( 2 ), the control means subtracts the output torque of the internal combustion engine corresponding to the second fuel injection amount in the second mode from the torque command calculated from the torque characteristics, The value is output to the power conversion means as a torque command based on the rotation speed deviation signal.

  As a result, the total output torque of the output torque of the motor generator and the output torque of the internal combustion engine is substantially similar to the output torque characteristic of the internal combustion engine for the same rotational speed deviation signal. The operating point (equilibrium point) at the time of the stop becomes close to the equilibrium point between the output torque of the internal combustion engine only and the drag resistance, and it is possible to smoothly shift to the operation of only the internal combustion engine.

( 5 ) In the above ( 2 ), the control means may output the torque command calculated from the torque characteristic as it is to the power conversion means as a torque command based on the rotation speed deviation signal.

Also in this case, when the rotation speed of the internal combustion engine reaches the vicinity of the target rotation speed, the control convergence process described in the above ( 1 ) is performed, so that it is possible to smoothly shift to the operation of only the internal combustion engine.

(6) In the above (1) to (5), preferably, the second fuel injection amount in the second mode, said in the first mode when the target rotational speed signal is idle speed This is a fuel injection amount corresponding to the first fuel injection amount based on the target rotational speed signal .

The I Ri簡 flight processing thereto can be obtained characteristics similar to the output torque commensurate with the dragging resistance of the internal combustion engine.

( 7 ) In the above (1) to ( 5 ), the second fuel injection amount in the second mode is determined in advance by a drag torque of a load corresponding to the actual rotational speed of the internal combustion engine. The drag torque corresponding to the actual rotational speed of the internal combustion engine at that time may be obtained from the drag torque value determined, and the fuel injection amount determined based on the torque value commensurate with the drag torque .

  As a result, even when the drag resistance fluctuates greatly in accordance with the actual rotational speed of the internal combustion engine, the second fuel injection amount corresponding to the drag resistance is calculated, so that the drag resistance is tracked. Thus, the output torque of the internal combustion engine can be appropriately controlled.

( 8 ) In the above (1) to ( 5 ), the second fuel injection amount in the second mode is a constant value that generates an output torque commensurate with the drag resistance of the internal combustion engine in the first mode. It may be.

  As a result, when the drag resistance does not change much with respect to the rotational speed of the internal combustion engine, the control configuration is simplified by setting the second fuel injection amount to a constant fuel injection amount that roughly matches the drag resistance. be able to.

  According to the present invention, in a construction machine equipped with a so-called all-speed control type internal combustion engine, during the so-called free accelerator operation in which the internal combustion engine rapidly increases the target rotational speed with almost no load, the motor generator assists driving. The smoke density can be improved and the increase in noise and fuel consumption can be suppressed. Further, the rotational speed of the internal combustion engine can be quickly increased to the vicinity of the target rotational speed by the assist drive of the motor generator based on the torque command based on the rotational speed deviation signal.

  In addition, according to the present invention, during the free accelerator operation of the internal combustion engine, the exhaust gas concentration can be improved and the increase in noise and fuel consumption can be suppressed by the assist drive of the motor generator, and at the time of driving only the internal combustion engine It is possible to quickly converge to an equilibrium point with drag resistance, and to suppress the deterioration of smoke density and the increase in noise and fuel consumption at that time.

  Embodiments of an internal combustion engine speed control device for a construction machine according to the present invention will be described below.

  FIG. 1 is a diagram showing an overall configuration of an internal combustion engine speed control device for a construction machine according to an embodiment of the present invention. In this embodiment, the present invention is applied when the construction machine is a hydraulic excavator.

  In FIG. 1, reference numeral 1 denotes an internal combustion engine provided in a hydraulic excavator. Input shafts of hydraulic pumps 5, 6, 7 are connected to an output shaft of the internal combustion engine 1, and the hydraulic pumps 5, 6, 7 are connected to the internal combustion engine 1. It is rotationally driven by. The hydraulic pumps 5 and 6 are variable displacement main pumps, and the hydraulic pump 7 is a fixed displacement pilot pump. Pressure oil discharged from the main pumps 5 and 6 is supplied to the hydraulic actuators 8, 9, 10, 11, for boom, arm, bucket, turning, right travel, and left travel via a control valve device (switching valve means) 14. 12 and 13. Corresponding to each of the hydraulic actuators 8, 9, 10, 11, 12, 13, operation lever devices (work machine operation command means) 19, 20, 21, 22, 23, 24 are provided, and the operation lever devices 19, 20 are provided. , 21, 22, 23, 24, the control valve device 14 is operated, and the hydraulic actuators 8, 9, 10, 11, 12, 13 are driven. The operation lever devices 19, 20, 21, 22, 23, and 24 are electric lever devices, and their operation commands are input to the controller 25. The controller 25 performs predetermined calculation processing based on these operation commands and outputs a drive signal corresponding to the control valve device 14. The control valve device 14 is actuated by these drive signals, and distributes the pressure oil discharged from the main pumps 5, 6 to the corresponding hydraulic actuators 8, 9, 10, 11, 12, 13. The hydraulic actuators 8, 9, 10, 11, 12, and 13 and the booms, arms, buckets, turning, right traveling, and left traveling driven members that constitute the hydraulic actuators 8, 9, 10, 11, 13 constitute a working machine that is driven by the internal combustion engine 1. .

  The internal combustion engine 1 is a diesel engine and includes an electronic governor (fuel injection amount control means) 2 that adjusts the fuel injection amount. The target engine speed signal of the internal combustion engine 1 is set by an engine control dial (target engine speed setting means) 18, and the electronic governor 2 operates based on the target engine speed signal.

  The internal combustion engine speed control apparatus according to the present embodiment is provided in the construction machine (hydraulic excavator) as described above, and transmits power to the output shaft of the internal combustion engine 1 and the input shafts of the hydraulic pumps 5, 6, 7. The motor generator 15 connected via a gear, the power storage device (power storage means) 17 connected so as to be able to transmit power between the motor generator 15, and the motor generator 15 and the power storage device 17 are installed. The power conversion device (power conversion means) 16, the rotation sensor (actual rotation speed detection means) 4 for detecting the actual rotation speed of the internal combustion engine 1, and the controller (control means) 25 are provided.

  As a first function, the controller 25 performs predetermined arithmetic processing based on the operation commands from the operation lever devices 19, 20, 21, 22, 23, and 24 as described above, and drives corresponding to the control valve device 14. Output a signal.

  In addition, the controller 25 has, as a second function, a target rotation speed command from the engine control dial 18, an operation command from the electric operation lever devices 19, 20, 21, 22, 23, 24, and a rotation sensor 4 An actual rotation speed signal and a voltage signal from a voltage sensor built in the power storage device 17 are input, a predetermined calculation process is performed, and a control signal is output to the electronic governor 2 and the power conversion device 16.

  Details of the second function of the controller 25 will be described.

  First, the fuel injection charge control of the all speed control method in the internal combustion engine 1 will be described.

  In the all-speed control type fuel injection charge control, a rotational speed deviation signal ΔN = Nr−Ne is obtained as a difference signal between the target rotational speed signal Nr from the engine control dial 18 and the actual rotational speed signal Ne from the rotation sensor 4. By calculating and instructing the fuel injection amount to the electronic governor 2 so that the rotational speed deviation signal ΔN approaches zero, the rotational speed and output torque of the internal combustion engine 1 are controlled.

  FIG. 2 is a diagram showing a fuel injection amount characteristic Q (ΔN) used in the all speed control method. This fuel injection amount characteristic Q (ΔN) is set so that the fuel injection amount Q increases linearly along the characteristic of the oblique straight line Q1 as the rotational speed deviation signal ΔN increases. Further, when the rotational speed deviation signal ΔN reaches a predetermined value ΔNa, the fuel injection amount Q becomes the maximum Qmax, and when the rotational speed deviation signal ΔN further increases, the fuel injection amount Q becomes a constant value of the maximum Qmax. Retained. In normal engine control, the fuel injection amount characteristic Q (ΔN) is stored, the corresponding rotational speed deviation signal ΔN is referred to the fuel injection amount characteristic Q (ΔN), and the corresponding fuel injection amount is obtained. The fuel injection amount is given as a target value to the electronic governor 2 to control the fuel injection amount.

  FIG. 3 is a diagram showing the output torque characteristic fe (ΔN) of the internal combustion engine 1 when the fuel injection amount is controlled as described above. This output torque characteristic fe (ΔN) corresponds to the fuel injection amount characteristic Q (ΔN), and as the rotational speed deviation signal ΔN increases, the output torque fe is linearly proportional to the characteristic of the oblique straight line fe1. It is set to increase. When the rotational speed deviation signal ΔN reaches a predetermined value ΔNa, the output torque fe reaches the maximum value femax. Even if the rotational speed deviation signal ΔN further increases, the output torque fe is a constant value of the maximum output torque femax. Retained.

  Here, the zero point of the fuel injection amount Q (ΔN) and the zero point of the torque characteristic fe (ΔN) do not coincide with each other because a loss corresponding to ΔT0 occurs due to internal friction of the internal combustion engine 1 or the like. The torque output to the outside of the internal combustion engine 1 exceeds zero after the rotational speed deviation signal exceeds ΔN3. Further, the torque characteristic fe (ΔN) of the internal combustion engine 1 slightly varies depending on the actual rotational speed, the intake air temperature, the intake air pressure, and the like.

  The fuel injection amount characteristic Q (ΔN) shown in FIG. 2 is set for each target rotational speed signal Nr, and the corresponding fuel injection amount characteristic Q (ΔN) is selected according to the target rotational speed signal Nr at that time, and the fuel injection The quantity Q is determined.

  FIG. 4 is a diagram showing the output torque characteristic Te (N) of the internal combustion engine 1 over the entire rotational speed range when the fuel injection amount is controlled by the fuel injection amount characteristic Q (ΔN) as shown in FIG. In the figure, the characteristics of the slanted straight lines R1, R2,..., Rn correspond to the characteristics of the slanted straight line fe1 of the torque characteristics fe (ΔN) in FIG. 3 and are the fuel injection amount control region (regulation region). . That is, the characteristics of the regulation regions of the straight lines R1, R2,..., Rn corresponding to the characteristics of the oblique straight line F1 of the torque characteristic fe (ΔN) of FIG. The torque values at the upper ends of these characteristics (straight lines R1, R2,..., Rn) correspond to the maximum output torque femax at the upper end of the straight line F1 of the torque characteristics fe (ΔN) in FIG. ..., the curve connecting the upper ends of Rn is the characteristic of the entire load region (region where the fuel injection amount is maximum). A straight line Tn shows the torque characteristic of the internal combustion engine 1 corresponding to zero fuel injection amount, and the rotational speed at the intersections P1, P2,..., Pn of the straight lines R1, R2,. Becomes the value (target rotational speed) of the target rotational speed signal Nr corresponding to the straight lines R1, R2,..., Rn.

  In the engine of the all speed control system as described above, for example, when the internal combustion engine 1 is started by setting the target rotational speed to the idling rotational speed by the engine control dial 18, the characteristic of the straight line R1 in FIG. 4 is obtained. At the idle speed, the operation lever devices 19, 20, 21, 22, 23, 24 are not normally operated, and the drag resistance Tw of the load connected to the internal combustion engine 1 and the output torque of the internal combustion engine 1 are balanced. The internal combustion engine 1 is operated at a point A on the straight line R1.

  Further, when the target rotational speed is set to the rotational speed corresponding to the straight line Rm by the engine control dial 18, the characteristic of the straight line Rm is obtained. In this case, when the operation lever devices 19, 20, 21, 22, 23, 24 are not operated, the drag resistance Tw of the load and the output torque of the internal combustion engine 1 are the same as when the idling speed is set. The internal combustion engine 1 is operated at a point D on the straight line Rm where the two are balanced.

  When any one of the operation lever devices 19, 20, 21, 22, 23, 24 is operated in this state, the pressure oil from the hydraulic pumps 5, 6 is supplied via the control valve device 14 to the hydraulic actuators 8, 9, 10, 11, 12, and 13 are supplied to perform the required work. At this time, the target rotational speed signal Nr, the actual rotational speed signal Ne, and the rotational speed deviation signal ΔN, which is a difference signal, change according to the load fluctuation of each hydraulic actuator, so that the fuel changes according to the change in the rotational speed deviation signal ΔN. The injection quantity changes, and the internal combustion engine 1 is operated mainly between the points D and C on the straight line Rm in FIG.

In the present embodiment, the second function of the controller 25 is based on the all-speed control method (rotational speed) using the fuel injection amount characteristic Q (ΔN) shown in FIG. 2 as the control mode of the fuel injection amount of the internal combustion engine 1. A mode in which the first fuel injection amount based on the deviation signal ΔN is commanded to the electronic governor 2 that is the fuel injection amount control means is set as the first mode, and separately from this, the load connected to the internal combustion engine 1 is pulled. A second fuel injection amount that generates an output torque that roughly matches the drag resistance (hereinafter simply referred to as a second fuel injection that roughly matches the drag resistance of the load) is commanded to the electronic governor 2 that is the fuel injection amount control means. The mode is set, the operation lever devices 19, 20, 21, 22, 23, 24 (work machine operation command means) are not operated, and the engine control dial (target speed setting means) 18 When operated in the target rotational speed increasing direction, the second mode is switched to command the second fuel injection amount to the electronic governor 2, and a torque command based on the rotational speed deviation signal ΔN is output to the power converter 16. The motor generator 15 is driven by the electric power from the power storage device 17, and assist driving by the motor generator 15 is performed. Further, after switching to the second mode, when the operation of the engine control dial 18 in the direction of increasing the target rotational speed is stopped and the rotational speed deviation signal ΔN enters a predetermined range, the fuel commanded to the electronic governor 2 the injection quantity is gradually increased or strike together from the second fuel injection amount of the second mode, gradually reducing the torque command to the power converter 16, the control mode of the final fuel injection amount shifts to the first mode The electronic governor 2 is made to command the first fuel injection amount in the first mode , and the torque command to the power converter 16 is stopped.

  In order to perform such control, the storage device of the controller 25 includes the fuel injection amount characteristic Q (ΔN) shown in FIG. 2 and the output torque characteristic fe (ΔN) of the internal combustion engine 1 shown in FIG. The output torque characteristic fm (ΔN) of the motor generator 15 shown in FIG.

  The output torque characteristic fm (ΔN) in FIG. 5 is used to calculate a torque command based on the rotational speed deviation signal ΔN. FIG. 5 also shows a fuel injection amount characteristic Q (ΔN) and an output torque characteristic fe (ΔN) for comparison. In FIG. 5, the torque characteristic fm (ΔN) is set so that the output torque fm increases linearly along the characteristic of the oblique straight line fm1 as the rotational speed deviation signal ΔN increases. When the rotational speed deviation signal ΔN reaches a predetermined value ΔNb, the output torque fm reaches the maximum value fmmax. Even if the rotational speed deviation signal ΔN further increases, the output torque fm is a constant value of the maximum output torque fmmax. Retained. The characteristic of the region of the straight line fm1 in which the torque command fm increases linearly in proportion to the increase in the rotational speed deviation signal ΔN in the torque characteristic fm (ΔN) is the straight line fe1 of the output torque characteristic fe (ΔN) of the internal combustion engine 1. It is set so as to approximate the characteristics (same slope).

  Hereinafter, the processing content performed by the second function of the controller 25 will be described with reference to the flowchart shown in FIG. The process shown in the flowchart of FIG. 6 is started at a predetermined time interval (for example, 10 ms).

  First, in step 101, various inputs inputted to the controller 25 are read. The inputs are the actual rotation speed signal from the rotation sensor 4, the storage voltage signal from the power storage device 17, the temperature signal of the power storage means, and the like, the target rotation speed signal from the engine control dial 18, and the operation lever devices 19, 20, 21, 22 , 23, 24, work machine operation command signals. Further, the difference between the target rotational speed signal Nr and the actual rotational speed signal Ne is calculated to obtain the rotational speed deviation signal ΔN.

  Next, in step 102, it is determined whether or not a work implement operation command has been issued based on the work implement operation command signal (whether at least one of the operation lever devices 19, 20, 21, 22, 23, and 24 has been operated). If the work implement operation command has been issued (Yes), the process proceeds to step 110. If the work implement operation command is not issued (No), the process proceeds to step 103.

  In step 110, the first mode using the fuel injection amount characteristic Q (ΔN) shown in FIG. 2 is selected as the control mode for the fuel injection amount of the internal combustion engine 1, and the fuel injection amount characteristic Q (ΔN) at that time is selected. The corresponding fuel injection amount Q is calculated with reference to the rotation speed deviation signal ΔN, and this fuel injection quantity Q is output to the electronic governor 2 as the first fuel injection quantity based on the rotation speed deviation signal ΔN. Further, the power converter 16 is instructed to stop the output, and the output torque from the motor generator 15 is made zero. Then, the process proceeds to “RETURN” and waits for the next processing.

  In step 103, it is determined whether or not the engine control dial 18 is operated in the target rotational speed increasing direction based on the target rotational speed signal Nr. If the engine control dial 18 is operated in the target rotational speed increasing direction (in the case of Yes), it is determined that the internal combustion engine 1 is in a free accelerator state and the routine proceeds to step 104. If the engine control dial 18 is not operated in the target rotational speed increasing direction, the routine proceeds to step 105.

  In step 104, the control mode of the fuel injection amount of the internal combustion engine 1 is switched from the first mode to the second mode, and a second value that roughly corresponds to the drag resistance Tw of the load connected to the electronic governor 2 to the internal combustion engine 1 is set. In addition to commanding the fuel injection amount, a torque command based on the rotational speed deviation signal ΔN is output to the power converter 16 to drive the motor generator 15 with the electric power from the power storage device 17, and assist drive by the motor generator 15 is performed. Do.

  Details of the processing content of step 104 will be described.

<Calculation of second fuel injection amount in second mode>
The calculation of the second fuel injection amount in the second mode in step 104 (the second fuel injection amount roughly commensurate with the drag resistance Tw of the load connected to the internal combustion engine 1) is, for example, the load connected to the internal combustion engine 1 As a value for calculating the second fuel injection amount roughly corresponding to the drag resistance Tw, a predetermined rotation speed deviation signal ΔN2 is predetermined and stored in the controller 25, and the fuel injection amount characteristic shown in FIG. The fuel injection amount Q (ΔN2) corresponding to Q (ΔN) is calculated by referring to the predetermined rotational speed deviation signal ΔN2.

  Here, how to determine the predetermined rotational speed deviation signal ΔN2 will be described.

  The predetermined rotational speed deviation signal ΔN2 is a value for calculating the second fuel injection amount that roughly matches the drag resistance Tw of the load connected to the internal combustion engine 1. Since the drag resistance Tw of the internal combustion engine 1 varies depending on the operating oil temperature of the hydraulic system including the hydraulic pumps 5 to 7 and the hydraulic actuators 8 to 13 or the presence or absence of an additional hydraulic pump, for example, on the straight line Rm in FIG. It is difficult to accurately predict the final equilibrium point such as point D in advance. Therefore, as a second best measure, a value smaller than and close to the rotational speed deviation signal ΔNd at the final equilibrium point D is determined as ΔN2. However, as a value smaller than and close to ΔNd corresponding to the final equilibrium point D, in this embodiment, the point A (target) on the straight line R1 in FIG. 4 is the point where the acceleration command for the internal combustion engine 1 is issued. Focusing on the rotational speed deviation ΔNg of the regulator region on the straight line R1 when the rotational speed is the idling rotational speed), the rotational speed deviation ΔNg is set as a predetermined rotational speed deviation signal ΔN2.

<Calculation of torque command based on rotation speed deviation signal ΔN>
The calculation of the torque command based on the rotational speed deviation signal ΔN in step 104 is performed by, for example, one of the following methods 1 and 2 using the torque characteristic fm (ΔN) shown in FIG.

  1. The output torque of the internal combustion engine 1 corresponding to the second fuel injection amount in the second mode is subtracted from the torque command calculated from the torque characteristic fm (ΔN), and the value is used as a torque command based on the rotational speed deviation signal. .

  2. The torque command calculated from the torque characteristic fm (ΔN) is directly used as the torque command based on the rotation speed deviation signal.

  Differences between the above methods 1 and 2 will be described with reference to FIG. FIG. 7 shows a state near the equilibrium point (point F in FIG. 7) when the free accelerator operation is performed when the torque command for the power converter 16 is calculated by the method 1 and when the torque command for the power converter 16 is calculated by the method 2. It is a figure which shows the change of each torque command and total output torque (total of the output torque of the motor generator 15, and the output torque of the internal combustion engine 1). In FIG. 7, Te indicates the output torque fe (ΔN2) of the internal combustion engine 1 when the rotational speed deviation ΔN is held at a constant value ΔN2 (the rotational speed deviation ΔNf at point A on the straight line R1 in FIG. 4). Shows the torque characteristics of the internal combustion engine 1 corresponding to the fuel injection amount zero as described above.

  When the torque fm obtained from the torque characteristic fm (ΔN) is commanded as it is as the output torque of the motor generator 15 as in the method 2, the total output torque obtained by adding the output torque of the motor generator 15 and the output torque of the internal combustion engine 1 is added. Since (total torque) is fm (ΔN) + fe (ΔN2), the equilibrium point with the drag resistance Tw connected to the internal combustion engine 1 is a point on the diagram of fm (ΔN) + fe (ΔN2) in FIG. E. Even if this equilibrium point E is a target, the point E is an equilibrium point between the output torque of only the internal combustion engine 1 and the drag torque Tw, which is relatively close to the point F on the diagram of fe (ΔN) in FIG. And almost fulfills the desired purpose. However, in order to further accelerate the convergence, it is preferable to set the output torque of the motor generator 15 to fm (ΔN) −fe (ΔN2) as in Method 1. By doing so, the total output torque obtained by adding the output torque fe (ΔN2) of the internal combustion engine 1 and the output torque fm (ΔN) −fe (ΔN2) of the motor generator 15 becomes fm (ΔN), and its characteristics Can be approximated to the torque characteristic fe (ΔN) in the first mode of the internal combustion engine 1 as shown in the diagram of fm (ΔN) in FIG. Therefore, in this case, the equilibrium point with the drag resistance Tw connected to the internal combustion engine 1 is very close to the point F on the diagram of fe (ΔN) in FIG. 7, and the output torque and drag of the internal combustion engine 1 only. It can be made to substantially coincide with the equilibrium point F with the torque Tw.

  For the above reason, Method 2 is adopted in the present embodiment, and fm (ΔN) −fe (ΔN2) is output to the power conversion device 16 as a torque command. The power conversion device 16 converts the power from the power storage device 17 in response to this torque command and outputs it to the motor generator 15 to obtain a desired output torque fm (ΔN) −fe (ΔN2).

  When the process of step 104 is completed, the process proceeds to “RETURN” and waits for the next process.

  When the determination result in step 103 is No, in step 105, it is determined whether or not the previous process is a process in the first mode, and if the previous process is a process in the first mode (in the case of Yes). Proceeds to step 110. When the previous process is not the first mode process (in the case of No), the operation of the engine control dial 18 is finished, but the actual engine speed of the internal combustion engine 1 has not yet reached the vicinity of the target engine speed. It is determined that it is in a state, and the process proceeds to step 106.

  In the processing after step 106, after the control mode of the fuel injection amount is switched to the second mode, the operation of the engine control dial 18 in the direction of increasing the target rotational speed is stopped and the rotational speed deviation signal ΔN is predetermined. When entering the range, the fuel injection amount commanded to the electronic governor 2 is gradually increased from the second fuel injection amount in the second mode to approach the first fuel injection amount in the first mode, and a torque command to the power converter 16 is issued. The fuel injection amount control mode is gradually shifted to the first mode, the electronic governor 2 is instructed to give the first fuel injection amount, and the torque command to the power converter 16 is stopped.

  That is, first, at step 106, a predetermined rotational speed deviation signal ΔN1 (see FIG. 7) is determined in advance as a value for determining whether or not the rotational speed of the internal combustion engine 1 has reached the vicinity of the target rotational speed. The rotation speed deviation signal ΔN is compared with the predetermined rotation speed deviation signal ΔN1. If the rotational speed deviation signal ΔN is larger than ΔN1 (in the case of No), it is determined that the rotational speed of the internal combustion engine 1 has not yet reached the vicinity of the target rotational speed, and the routine proceeds to step 104. If the absolute value of the rotational speed deviation signal ΔN is equal to or smaller than ΔN1 (in the case of Yes), it is determined that the rotational speed of the internal combustion engine 1 has reached the vicinity of the target rotational speed, and the routine proceeds to step 107 to control the fuel injection amount control mode. Is started (switched) from the second mode to the first mode.

The predetermined rotational speed deviation signal ΔN1 does not exceed the rotational speed deviation ΔNa corresponding to the maximum output torque femax of the output torque characteristic fe (ΔN) of the internal combustion engine 1 shown in FIG. A value close to the rotation speed deviation signal ΔNf in the vicinity of the intersection of fe (ΔN) and Tw is desirable. For example, since in the normal rotational speed deviation signal .DELTA.N the torque value of the output torque characteristics fe (.DELTA.N) is maximized is about 100～200Min ^-1, preferably more than about 50min ^-1 as predetermined rotational speed deviation signal ΔN1 More preferably, it is about 20 min ⁻¹ .

  In step 107, the output torque of the internal combustion engine 1 is increased stepwise so that the fuel injection amount control mode smoothly shifts from the second mode to the first mode, and is determined in advance as a predetermined rotational speed deviation signal ΔN2. The increment δN2 thus obtained is added, and this is used as a new rotational speed deviation signal ΔN2, and the routine proceeds to step 108.

  Here, in step 104, when the fuel injection amount control is performed based on the new rotation speed deviation signal ΔN2, the fuel injection amount is calculated as Q (ΔN2) using the fuel injection amount characteristic Q (ΔN), and the power Since the torque command for the conversion device 16 is calculated as fm (ΔN) −fe (ΔN2), the fuel injection amount of the electronic governor 2 increases to increase the output torque of the internal combustion engine 1, and the motor generation by the increase. The output torque of the machine 15 decreases. As a result, by repeating the process of adding the increment δN2 to the rotational speed deviation signal ΔN2 in step 104, the output torque fe (ΔN2) of the internal combustion engine 1 and the output torque fm (ΔN) −fe (ΔN2) of the motor generator 15 , While maintaining their total output torque at fm (ΔN), broken line arrows from point G to point F (internal combustion engine output torque) and point H to point M (motor generator output torque) in FIG. 7 respectively. Migrate like this.

  In step 108, in order to determine whether or not the total output torque fm (ΔN) has approached the final equilibrium point F to a degree sufficient to switch the control mode of the fuel injection amount to the first mode, the total output torque fm (ΔN ) And the output torque fe (ΔN2) of the internal combustion engine 1 (for example, the difference in torque between the point J and the point L in FIG. 7), fm (ΔN) −fe (ΔN2), and the absolute value | fm It is determined whether (ΔN) −fe (ΔN2) | is equal to or smaller than a predetermined allowable value ε. If | fm (ΔN) −fe (ΔN2) | ≦ ε, the process proceeds to step 104 to continue the process. If | fm (ΔN) −fe (ΔN2) | ≦ ε, it is determined that the total output torque fm (ΔN) has reached the vicinity of the target equilibrium point F, and the routine proceeds to step 109.

  Note that the absolute value | fm (ΔN) −fe (ΔN2) | of the difference between the total output torque fm (ΔN) and the output torque fe (ΔN2) of the internal combustion engine 1 is determined as the processing content of step 108. Although it has been described that it is determined whether or not it is equal to or less than the value ε, the calculated value fm (ΔN) −fe (ΔN2) results in the torque command for the power converter 16 being equal to fm (ΔN) −fe (ΔN2). The determination is that the torque command for the power converter 16 is fm (ΔN) −fe (ΔN2), and it is determined whether or not the value at the K point is less than or equal to the allowable value ε (whether or not it has approached 0). Is equivalent.

  In step 109, in order to return the rotation speed deviation signal ΔN2 repeatedly increased in the processing in step 107, ΔN20 predetermined as the initial value is set as a new ΔN2, and the process proceeds to step 110.

  In step 110, as described above, the first mode using the fuel injection amount characteristic Q (ΔN) shown in FIG. 2 is selected as the fuel injection amount control mode of the internal combustion engine 1, and the fuel injection amount characteristic Q (ΔN ) Is calculated with reference to the rotational speed deviation signal ΔN at that time, and this fuel injection quantity Q is output to the electronic governor 2 as the first fuel injection quantity based on the rotational speed deviation signal ΔN. . Further, the power converter 16 is instructed to stop the output, and the output torque from the motor generator 15 is made zero. Then, the process proceeds to “RETURN” and waits for the next processing.

  The operation of the present embodiment configured as described above will be described.

  First, the case where the internal combustion engine 1 is started by setting the target rotational speed to the idling rotational speed with the engine control dial 18 will be described. When starting the internal combustion engine 1 with the target rotational speed set to the idling rotational speed, the operating lever devices 19, 20, 21, 22, 23, and 24 are not operated and the engine control dial 18 is in the direction of increasing the target rotational speed. Since it is not operated, the controller 25 calculates a rotational speed deviation signal ΔN = Nr−Ne as a difference signal between the target rotational speed signal Nr from the engine control dial 18 and the actual rotational speed signal Ne from the rotational sensor 4. (Step S101) After that, the first mode using the fuel injection amount characteristic Q (ΔN) shown in FIG. 2 is selected as the control mode of the fuel injection amount of the internal combustion engine 1 (Step 101 → 102 → 103 → 105 → 110). In this first mode, the fuel injection amount Q corresponding to the fuel injection amount characteristic Q (ΔN) is calculated with reference to the rotational speed deviation signal ΔN at that time, and this fuel injection amount Q is calculated based on the rotational speed deviation signal ΔN. The first fuel injection amount is output to the electronic governor 2 and the power converter 16 is instructed to stop the output so that the output torque from the motor generator 15 is zero. Thus, the characteristic of the straight line R1 in FIG. 4 is obtained, and the fuel injection amount is controlled so that the rotational speed deviation signal ΔN approaches zero on the characteristic line of the straight line R1 in FIG. The internal combustion engine 1 is operated at a point A on the straight line R1 where the drag resistance Tw of the engine and the output torque of the internal combustion engine 1 are balanced.

  Next, when the internal combustion engine 1 is in a substantially no-load state, the engine control dial 18 is rapidly operated to increase the target rotational speed of the internal combustion engine 1 to a value corresponding to the straight line Rm in FIG. Will be described. At the time of this free accelerator operation, the work machine operation command is not issued, and the engine control dial 18 is operated in the direction of increasing the target rotational speed, so the controller 25 sets the fuel injection amount control mode of the internal combustion engine 1 to the first mode. By switching from the first mode to the second mode, the electronic governor 2 is instructed with a second fuel injection amount (Q (ΔN2)) roughly corresponding to the drag resistance Tw of the load connected to the internal combustion engine 1, and the rotational speed deviation A torque command (fm (ΔN) −fe (ΔN2)) based on the signal ΔN is output to the power converter 16 to drive the motor generator 15 with the electric power from the power storage device 17, and assist driving by the motor generator 15 is performed. Perform (Step 101 → 102 → 103 → 104). After the control mode of the fuel injection amount is switched to the second mode, the operation of the engine control dial 18 in the target rotational speed increasing direction is stopped and the rotational speed deviation signal ΔN becomes smaller than the predetermined rotational speed deviation signal ΔN1 in advance. The above control is continued until a predetermined range is set (step 101 → 102 → 103 → 105 → 106 → 104).

  As a result, the internal combustion engine 1 is not only assisted driven by the motor generator 15 but also the fuel injection amount of the internal combustion engine 1 can be suppressed to the minimum fuel injection amount commensurate with the drag resistance. In addition, an increase in noise and fuel consumption can be suppressed.

  At this time, the motor generator 15 is driven based on the torque command based on the rotation speed deviation signal, and the internal combustion engine 1 receives the assist drive torque by the motor operation of the motor generator 15. Can be quickly increased to the vicinity of the target rotational speed.

  Thereafter, when the rotational speed deviation signal ΔN becomes smaller than the predetermined rotational speed deviation signal ΔN1 (that is, when entering the predetermined range), it is determined that the rotational speed of the internal combustion engine 1 has reached the vicinity of the target rotational speed. By adding a predetermined increment δN2 to the rotational speed deviation signal ΔN2, the fuel injection amount commanded to the electronic governor 2 is gradually increased from the second fuel injection amount in the second mode, and the first fuel injection in the first mode. The torque command to the power converter 16 is gradually reduced (point H → point K in FIG. 7) (step 101 → 102 → 103 → 105 → 106 → 107 →). 108 → 104) Finally, the control mode of the fuel injection amount is shifted to the first mode, the electronic governor 2 is instructed to give the first fuel injection amount, and the torque command to the power converter 16 is stopped (FIG. 7). Point F) (step 101 → 102 → 103 → 105 → 106 → 107 → 108 → 109 → 110).

  Thereby, after the rotational speed of the internal combustion engine 1 reaches the vicinity of the target rotational speed, the assist drive by the motor generator 15 is smoothly stopped, and the operation state based on the rotational speed deviation signal only by the normal internal combustion engine 1 is restored. It is possible to quickly converge to a new equilibrium point F where the output torque and drag resistance of only the internal combustion engine 1 are balanced, and to suppress deterioration in smoke concentration and increase in noise at that time.

  The effect of the present embodiment will be described in more detail in comparison with the prior art.

As described above, the device described in Patent Document 2 (Japanese Patent Laid-Open No. 2-206302) has a predetermined exhaust particle concentration based on the rotational speed of the internal combustion engine and the exhaust particle concentration characteristic specific to the internal combustion engine. While obtaining the torque command value corresponding to the rotational speed at that time from the torque command pattern to be suppressed, a drive torque reduction signal with a magnification from zero to 1 corresponding to the depression angle of the accelerator pedal is obtained, and multiplied by them to calculate the motor A drive torque command value is obtained, and the motor is driven to assist the drive torque so that the drive torque command value is obtained. During the assist drive by the electric motor, no special control for reducing the smoke concentration is performed on the internal combustion engine.

Here, the control of the fuel injection amount of an internal combustion engine (diesel engine) mounted on a normal vehicle as described in Patent Document 2 is a so-called minimum maximum in which the fuel injection amount is determined based on the accelerator opening and the rotational speed. The characteristics of the speed control method are adopted. FIG. 8 shows the output torque characteristics of the internal combustion engine over the entire rotational speed range when the fuel injection amount is controlled by the characteristics of the minimum maximum speed control system. In the minimum maximum speed control method, as shown in FIG. 8, output torque characteristics S1 to Sn are set so that the maximum output torque changes according to the depression angle of the accelerator pedal. Therefore, when the accelerator pedal depression angle is operated to an opening in the intermediate region where the accelerator pedal depression angle is not the maximum and, for example, the output torque characteristic S2 is set , the fuel injection amount increases as the accelerator pedal depression angle increases, and the internal combustion engine output torque and changes as the point A1 → B1 → D1 along the output torque characteristic S2 of FIG. 8, a new equilibrium point from the equilibrium point a and drag resistance Tw of the load connected to the internal combustion engine Move to D1. During this time, the injection amount corresponding to the depression angle of the accelerator pedal is stopped at the maximum, so that there is no excessive injection amount. As a result, the apparatus of Patent Document 2 is special for the internal combustion engine only by driving the motor and assisting the drive torque at the time of so-called free acceleration in which the internal combustion engine increases the target rotational speed rapidly with almost no load. Even if the control is not performed, it is possible to prevent the internal combustion engine from generating a large torque especially in the low speed region in accordance with the autonomous injection amount control, and to prevent the smoke concentration from deteriorating.

  On the other hand, in the conventional speed control device for the internal combustion engine 1 of the so-called all-speed control method having an output torque characteristic as shown in FIG. Since the fuel injection amount is determined according to the rotational speed deviation ΔN, which is the difference in rotational speed, even if the accelerator is operated to the opening of the intermediate region as described above, if the control dial 18 is operated at a normal speed, The number deviation signal ΔN suddenly increases. As a result, a large fuel injection amount commensurate with the rotational speed deviation signal ΔN is calculated by the fuel injection amount characteristic Q (ΔN) of FIG. 2 and commanded to the electronic governor 2. In this case, when the rotational speed deviation signal ΔN exceeds the value ΔNa corresponding to the maximum fuel injection amount Qmax, the maximum fuel injection amount Qmax is limited (point B). Then, the internal combustion engine 1 is accelerated with the output torque corresponding to the maximum fuel injection amount Qmax (point B-point C), and the rotational speed deviation signal becomes smaller as the target rotational speed is approached, so the fuel injection amount decreases. Eventually, the output torque is balanced at a new equilibrium point D with the drag resistance Tw, and the internal combustion engine 1 continues to operate at the actual rotational speed and output torque at the point D. In this process, the internal combustion engine 1 is operated by receiving a large fuel injection amount from the low speed region, so that the smoke concentration is deteriorated and the noise and fuel consumption are also adversely affected.

  In contrast to such a conventional technique, in the present embodiment, the internal combustion engine 1 is in an unloaded state in which the operation lever devices 19, 20, 21, 22, 23, 24 (work machine operation command means) are not operated. When the engine control dial 1 (target rotational speed setting means) is operated in the state of increasing the target rotational speed in the state, the fuel injection amount of the internal combustion engine 1 is the drag of the load connected to the internal combustion engine 1. Since it is switched to the second fuel injection amount that roughly matches the resistance Tw, the fuel injection amount of the internal combustion engine 1 is suppressed to the minimum fuel injection amount that can counter the drag resistance Tw, and the deterioration of the flue gas concentration is suppressed. Is done. Further, at this time, since the internal combustion engine 1 receives the assist driving torque by the motor operation of the motor generator 15, the rotational speed of the internal combustion engine 1 can be quickly increased to the vicinity of the target rotational speed. Further, the assist by the motor generator 15 is smoothly stopped after the rotational speed of the internal combustion engine 1 reaches the vicinity of the target rotational speed, and the operation state based on the rotational speed deviation signal by only the normal internal combustion engine 1 is restored. As a result, it is possible to quickly converge to a new equilibrium point F where the output torque and drag resistance of only the internal combustion engine 1 are balanced, and to suppress the deterioration of the flue gas concentration and the increase in noise at that time.

  Although one embodiment of the present invention has been described above, the present embodiment can be variously modified within the spirit of the present invention. For example, in step 104 of the flowchart shown in FIG. 6, in the second mode of fuel injection amount control of the internal combustion engine 1, the second fuel injection amount that roughly matches the drag resistance Tw of the load connected to the internal combustion engine 1 is The fuel injection amount Q (ΔN2) calculated by the fuel injection amount characteristic Q (ΔN) shown in FIG. 2 using the predetermined rotation speed deviation signal ΔN2 is used. However, the drag resistance of the internal combustion engine 1 becomes the actual rotation speed Ne. On the other hand, when it fluctuates significantly, the second fuel injection amount in the second mode may be the fuel injection amount obtained from the torque characteristic set with respect to the actual rotational speed in accordance with the actual drag resistance. In this case, for example, in step 104, instead of obtaining the fuel injection amount (second fuel injection amount) by Q = Q (ΔN2), the internal combustion engine 1 that is determined in advance by approximating the drag resistance Tw of FIG. A torque value corresponding to the actual rotational speed at that time is obtained from the drag torque value assumed for the actual rotational speed, and the torque is calculated from the torque characteristic fe (ΔN) of the internal combustion engine 1 shown in FIGS. A rotational speed deviation ΔN3 corresponding to the value is obtained, and the rotational speed deviation ΔN3 is referred to the fuel injection amount characteristic Q (ΔN) shown in FIGS. 2 and 5 to correspond to the fuel injection amount (second fuel injection amount). And the fuel injection amount is commanded to the electronic governor 2. Further, a torque command corresponding to the rotational speed deviation ΔN3 at this time is calculated by, for example, torque command = fm (ΔN) −fe (ΔN3), and is output to the power conversion device 16. Thereafter, when the process first proceeds to step 107 in the flowchart of FIG. 6, the rotational speed deviation ΔN corresponding to the output torque of the internal combustion engine 1 at that time is obtained from the torque characteristic fe (ΔN) of FIG. The increment δN2 is added as a predetermined rotational speed deviation ΔN2 to obtain a new rotational speed deviation signal ΔN2, and the subsequent processing may be performed.

  When the circulating oil viscosity of the internal combustion engine becomes high in a low temperature environment or when a large capacity fixed displacement hydraulic pump is mounted on the internal combustion engine, the drag resistance of the internal combustion engine 1 is significantly higher than the actual rotational speed Ne. Fluctuates. Thus, even if the drag resistance varies greatly according to the actual rotational speed of the internal combustion engine, the second fuel injection amount corresponding to the drag resistance is calculated by the above configuration. Therefore, the output torque of the internal combustion engine 1 can be appropriately controlled following the variation in drag resistance.

  If the drag resistance does not change much with respect to the rotational speed of the internal combustion engine 1, the second fuel injection amount used in the second mode roughly matches the drag resistance in step 104 of the flowchart shown in FIG. It may be a predetermined constant value. In this case, for example, instead of obtaining the fuel injection amount (second fuel injection amount) by Q = Q (ΔN2), the torque characteristics of the internal combustion engine 1 shown in FIGS. 3 and 5 are always used by using a constant output torque value. A revolution speed deviation ΔN4 (constant value) corresponding to the torque value is obtained from fe (ΔN), and the revolution speed deviation ΔN4 is further referred to by referring to the fuel injection amount characteristic Q (ΔN) shown in FIGS. The fuel injection amount (constant value; second fuel injection amount) to be obtained is obtained, and this fuel injection amount is commanded to the electronic governor 2. Further, a torque command corresponding to the rotational speed deviation ΔN3 at this time is calculated by, for example, torque command = fm (ΔN) −fe (ΔN4), and is output to the power converter 16. When the routine first proceeds to step 107, similarly to the above, the rotational speed deviation ΔN corresponding to the output torque of the internal combustion engine 1 at that time is obtained from the torque characteristic fe (ΔN) of FIG. What is necessary is just to set it as rotation speed deviation (DELTA) N2.

  Thus, since the second fuel injection amount and the torque command for the motor generator 15 are respectively constant values, the control configuration can be simplified.

  In the above description, only the case where the motor generator 15 is driven by the electric power from the power storage device 17 has been described. However, the surplus power of the internal combustion engine 1 is utilized by a known means, and a command from the power conversion device 16 is used. Thus, the motor generator 15 may be caused to perform a generator operation so that electric power is stored in the power storage device 17 to supplement the power consumption when the motor is operated. It is also preferable to provide power recovery means and drive the motor generator 15 with the recovered power to convert it into electric power and store it in the power storage device 16.

1 is a diagram illustrating an overall configuration of an internal combustion engine speed control device for a construction machine according to an embodiment of the present invention. It is a figure which shows the fuel injection quantity characteristic Q ((DELTA) N) used with an all speed control system. It is a figure which shows the output torque characteristic fe ((DELTA) N) of an internal combustion engine when the fuel injection quantity is controlled by the all speed control system. It is a figure which shows the output torque characteristic Te (N) of the internal combustion engine 1 over the whole rotation speed range when the fuel injection quantity is controlled by the all speed control system. It is a figure which shows the output torque characteristic fm ((DELTA) N) of the motor generator used for calculating the torque command based on the rotation speed deviation signal (DELTA) N. It is a flowchart which shows the processing content which the 2nd function of a controller performs. It is explanatory drawing which shows the torque command with respect to the power converter device in the vicinity of the equilibrium point (F point in FIG. 7) at the time of free accelerator operation, and the change of a total output torque. It is a figure which shows the output characteristic of an internal combustion engine in case the control of the injection quantity of an internal combustion engine has the characteristic of the minimum maximum speed control system.

Explanation of symbols

1 Internal combustion engine 2 Electronic governor (fuel injection amount control device)
4 Rotation sensor (Actual rotational speed detection means)
5, 6, 7 Hydraulic pump 8, 9, 10, 11, 12, 13 Hydraulic actuator 14 Control valve device 15 Motor generator 16 Power conversion device 17 Power storage device 18 Engine control dial (target rotational speed setting means)
19, 20, 21, 22, 23, 24 Operation lever device 25 Controller

Claims (8)

An internal combustion engine;
A working machine driven by the internal combustion engine;
A work implement operation command means for outputting an operation command for the work implement;
Fuel injection amount control means for adjusting the fuel injection amount of the internal combustion engine;
Target rotational speed setting means for outputting a target rotational speed signal for setting the target rotational speed of the internal combustion engine, the target rotational speed setting means for increasing or decreasing the target rotational speed when operated ,
An actual rotational speed detecting means for detecting the actual rotational speed of the internal combustion engine,
Wherein the fuel injection amount control of the first fuel injection amount based on the rotation speed deviation signal which is the difference signal between the actual speed signal of the target rotational speed signal from the actual rotation speed detecting means from the target rotational speed setting means In the internal combustion engine speed control device of the work machine that commands the means,
A motor generator coupled to the internal combustion engine;
Power storage means connected to the motor generator so as to be able to transmit power; and
Power conversion means installed between the motor generator and the power storage means;
A mode in which the first fuel injection amount based on the rotation speed deviation signal is commanded to the fuel injection amount control means is set as a first mode, and separately from this, the drag resistance of the load connected to the internal combustion engine is set. A second mode for instructing the fuel injection amount control means to generate a second fuel injection amount that generates an output torque that is roughly commensurate is set, the work implement operation instruction means is not operated, and the target rotational speed setting means is When operated in the target rotational speed increasing direction, the second mode is switched to command the second fuel injection amount to the fuel injection amount control means, and the torque command based on the rotational speed deviation signal is converted to the power conversion Control means for driving the motor generator with electric power from the power storage means and outputting to the means ,
The control means, after switching to the second mode, when the operation of the target rotational speed setting means in the direction of increasing the target rotational speed stops and the rotational speed deviation signal enters a predetermined range. The fuel injection amount commanded to the fuel injection amount control means is gradually increased from the second fuel injection amount, the torque command for the power conversion means is gradually decreased, and finally the control mode of the fuel injection amount control means shifts to the first mode the first fuel injection amount in the first mode command to the fuel injection quantity control means, and characterized that you stop the output of the torque command to the power converter unit Internal combustion engine speed control device. The internal combustion engine speed control device for a work machine according to claim 1,
In the second mode, the control means calculates a torque command from a torque characteristic that is set so that the torque command increases in response to an increase in the rotational speed deviation signal, and based on the torque command, torque for the power conversion means is calculated. An internal combustion engine speed control apparatus characterized by determining a command. The internal combustion engine speed control device for a work machine according to claim 2 ,
The torque characteristic is set to approximate the torque characteristic of the internal combustion engine corresponding to the first fuel injection amount in the first mode in a region where the torque command increases in response to an increase in the rotation speed deviation signal. An internal combustion engine speed control device. The internal combustion engine speed control device for a work machine according to claim 2 ,
The control means subtracts the output torque of the internal combustion engine corresponding to the second fuel injection amount in the second mode from the torque command calculated from the torque characteristics, and the value is based on the rotation speed deviation signal. An internal combustion engine speed control device that outputs the torque command to the power conversion means. The internal combustion engine speed control device for a work machine according to claim 2 ,
The internal combustion engine speed control device, wherein the control means outputs the torque command calculated from the torque characteristics to the power conversion means as it is as a torque command based on the speed deviation signal. In the internal-combustion-engine speed control apparatus of the working machine of any one of Claims 1-5 ,
The second fuel injection amount in the second mode corresponds to the first fuel injection amount based on the target rotational speed signal when the target rotational speed signal is the idling rotational speed in the first mode. An internal-combustion-engine speed control device characterized by being an amount. In the internal-combustion-engine speed control apparatus of the working machine of any one of Claims 1-5 ,
As the second fuel injection amount in the second mode, a drag torque of a load corresponding to the actual rotational speed of the internal combustion engine is determined in advance , and the internal combustion engine at that time is determined from the predetermined drag torque value. An internal combustion engine speed control device characterized in that a drag torque corresponding to the actual engine speed is obtained and a fuel injection amount determined based on a torque value commensurate with the drag torque . In the internal-combustion-engine speed control apparatus of the working machine of any one of Claims 1-5 ,
The internal combustion engine speed control apparatus according to claim 1, wherein the second fuel injection amount in the second mode is a constant value that generates an output torque commensurate with a drag resistance of the internal combustion engine in the first mode .

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